The Tech Report published a bit more information about Seasonic's X-Series power supplies, which feature an efficiency of 90 percent at 50 percent load and at least 87 percent at 20 percent load and full load.
The firm's new X-Series power supply series include 650W and 750W models, both of which have 80 Plus Gold certification. That means the unit reaches a 90% efficiency level when it's loaded to 50%. (Efficiency at 20% and 100% loads is a lesser but still impressive 87%.)
Even more interesting is the X-Series internal design, which looks surprisingly bare compared to traditional units crammed with heatsinks and capacitors. Seasonic wouldn't let us take pictures, but it uses a second circuit board stuck right up against the modular connectors at the back to reduce the number of wires inside the casing. Also, presumably, the high efficiency should mean the internal components generate less heat, which in turn requires less cooling.
These new units will be available in late July or early August.